Former New England Patriots player Aaron Hernandez is awaiting trial on murder charges in a 2013 shooting near his home. / Matt Stone, Reuters pool

by Lindsay H. Jones, USA TODAY Sports

by Lindsay H. Jones, USA TODAY Sports

If juries ultimately believe what prosecutors and police in Massachusetts allege, former New England Patriots tight end Aaron Hernandez isn't just the man who orchestrated the killing of his friend, Odin Lloyd.

He's a man who police say killed three people, and tried to kill more.

But this doesn't necessarily mean Hernandez is a serial killer, said Helen Morrison, a forensic psychiatrist who has done extensive research on some of America's most notorious killers.

"A serial killer is a person with a very severe lack of personality structure. He's not a person," Morrison told USA TODAY Sports prior to two new murder indictments that were made public Thursday. "The serial killer just almost has a sense of continuing to kill as an act. It doesn't have any motive. It doesn't have emotion attached to it. It doesn't fit in the context or anger or revenge or the things that we think people commit homicides for."

Those new alleged murders are unrelated to the Lloyd case.

Hernandez last year was charged with first-degree murder in the Lloyd case after the 27-year-old semi-pro football player's bullet-riddled body was discovered less than a mile from Hernandez's home on June 17. On Thursday, a grand jury in Boston indicted Hernandez on murder charges in the July 2012 shooting deaths of Safiro Furtado and Daniel Abreu. The two men were shot while in their vehicle after leaving a Boston nightclub where Hernandez had also been.

Suffolk County District Attorney Daniel F. Conley accused Hernandez of firing the fatal shots and then working to conceal evidence, including hiding the SUV in which he was riding in a relative's garage in Connecticut.

The murders had been under investigation for nearly a year before a link to Hernandez was discovered during the investigation into Lloyd's murder.

Morrison said she is intrigued by what might have gone on inside Hernandez's brain and what events had happened in his life.

"What we see in this guy, Hernandez, is motive. Anger and rage are motive. Whether he thinks he's being wronged or taken advantage, he's just going to kill people," Morrison said. "He just seems to be a guy with a tremendous amount of rage. He doesn't seem to be psychotic or mentally ill, like a lot of the mass shooters are, just sort of does what he wants to do. "

Morrison said the fact that Hernandez surrounded himself by friends is another element that distinguishes him from traditional serial killers, who tend to be loners.

Police say Hernandez was joined by two associates, Ernest Wallace and Carlos Ortiz, on the night Lloyd was killed.

"[Serial killers] have no attachment to human beings," Morrison said. "This guy seems to have had a posse, obviously they admire him, would go along with almost anything he said. The celebrity groupie person will forgive anything, as long as they were with this guy."

Much has been made since Hernandez was first linked to the Lloyd homicide investigation about Hernandez's potential ties to gangs from his hometown in Connecticut. He was asked about gang affiliations and had his tattoos examined by jail officials after his arrest last June.

There have been no definitive links to any gang activity, but a gang culture expert told USA TODAY Sports that Hernandez appears to have adhered to a "street code" in his personal life.

Dr. Carl Taylor, a sociology professor at Michigan State who has studied gang culture for more than 30 years, said his observations of Hernandez's behavior after his televised arrest and subsequent court hearings last year brought to mind old-school mobsters, an organized crime boss rather than petty criminal.

"This is not simply about gang signs. This is being a gangster at a high level," Taylor said prior to the two new indictments. "He doesn't seem to be shaken."

Morrison said she does not believe there is any connection between Hernandez's background playing football and his alleged violent behavior. If she had the chance to study or interview him, Morrison said she would focus on Hernandez's childhood and family history.

"A whole bunch of things to find out how, up until age 18, how did this kid function?" Morrison said. "Because you can't build a building without a foundation, and nobody just wakes up one day and becomes a murderer, or becomes narcissistic personality disorder. That is definitely developmental."